I'm guessing here, but perhaps the conversation was based on the amount of oxygen getting to your mother's heart. Oxygen is carried by the blood to the heart tissue/muscle. By the fact you are posting on this board, I suspect your mother has congestive heart failure, and it is extremely common for those of us with that condition to have problems getting oxygen to the heart as the blood supply is diminished.
No. Someone who is either mentally challenged, or received their medical credential with boxtops provided you with that answer. That is not to say that something is not seriously wrong with your loved one's heart. Then again the problem may not be so serious. Stop worrying. Things may not be as bad as you think . I suggest you find an adult who is familiar with your mother's condition to speak with.